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NHTSA Interpretation File Search

Overview

NHTSA's Chief Counsel interprets the statutes that the agency administers and the standards and regulations that it issues. Members of the public may submit requests for interpretation, and the Chief Counsel will respond with a letter of interpretation. These interpretation letters look at the particular facts presented in the question and explain the agency’s opinion on how the law applies given those facts. These letters of interpretation are guidance documents. They do not have the force and effect of law and are not meant to bind the public in any way. They are intended only to provide information to the public regarding existing requirements under the law or agency policies. 

Understanding NHTSA’s Online Interpretation Files

NHTSA makes its letters of interpretation available to the public on this webpage. 

An interpretation letter represents the opinion of the Chief Counsel based on the facts of individual cases at the time the letter was written. While these letters may be helpful in determining how the agency might answer a question that another person has if that question is similar to a previously considered question, do not assume that a prior interpretation will necessarily apply to your situation.

  • Your facts may be sufficiently different from those presented in prior interpretations, such that the agency's answer to you might be different from the answer in the prior interpretation letter;
  • Your situation may be completely new to the agency and not addressed in an existing interpretation letter;
  • The agency's safety standards or regulations may have changed since the prior interpretation letter was written so that the agency's prior interpretation no longer applies; or
  • Some combination of the above, or other, factors.

Searching NHTSA’s Online Interpretation Files

Before beginning a search, it’s important to understand how this online search works. Below we provide some examples of searches you can run. In some cases, the search results may include words similar to what you searched because it utilizes a fuzzy search algorithm.

Single word search

 Example: car
 Result: Any document containing that word.

Multiple word search

 Example: car seat requirements
 Result: Any document containing any of these words.

Connector word search

 Example: car AND seat AND requirements
 Result: Any document containing all of these words.

 Note: Search operators such as AND or OR must be in all capital letters.

Phrase in double quotes

 Example: "headlamp function"
 Result: Any document with that phrase.

Conjunctive search

Example: functionally AND minima
Result: Any document with both of those words.

Wildcard

Example: headl*
Result: Any document with a word beginning with those letters (e.g., headlamp, headlight, headlamps).

Example: no*compl*
Result: Any document beginning with the letters “no” followed by the letters “compl” (e.g., noncompliance, non-complying).

Not

Example: headlamp NOT crash
Result: Any document containing the word “headlamp” and not the word “crash.”

Complex searches

You can combine search operators to write more targeted searches.

Note: The database does not currently support phrase searches with wildcards (e.g., “make* inoperative”). 

Example: Headl* AND (supplement* OR auxiliary OR impair*)
Result: Any document containing words that are variants of “headlamp” (headlamp, headlights, etc.) and also containing a variant of “supplement” (supplement, supplemental, etc.) or “impair” (impair, impairment, etc.) or the word “auxiliary.”

Search Tool

NHTSA's Interpretation Files Search



Displaying 11671 - 11680 of 16517
Interpretations Date

ID: nht90-1.33

Open

TYPE: INTERPRETATION-NHTSA

DATE: FEBRUARY 1, 1990

FROM: HERBERT E. STOEL

TO: JOHN WOMACK -- DEPARTMENT OF TRANSPORTATION

TITLE: NONE

ATTACHMT: ATTACHED TO LETTER DATED 4-8-90 TO HERBERT E. STOEL FROM STEPHEN P. WOOD; (A35; STD. 108). ALSO ATTACHED TO LETTER DATED 12-30-87 TO KEN SIKKEMA FROM HERBERT E. STOEL. TEXT:

For quite some time, I have been deeply concerned about the need for greater safety on our highways. Back in August 1971, I gave a letter to former President Gerald R. Ford who was then a United States Congressman, stating the need for a change in the t aillights on all cars and trucks. The change would be green taillights and red stoplights. RED should mean only one thing, STOP.

Then on December 30, 1987, I gave a letter to Michigan State Representative Mr. Ken Sikkema (see letter enclosed), and now I feel inclined to bring this matter to your attention, because you have the authority to act on it. We have a law demanding the u se of seat belts or air bags on all cars, but it is more important to go even further and get to the origin of the problem. (A better warning of impending danger up front.)

So if we had Green taillights and Red stoplights, it would carry out the same system as our traffic lights, thus the idea would be received without confusion.

May it be found in your good pleasure and authority to enact this change before Japan or some other foreign nation forces us into it.

Enclosure

ID: nht90-1.34

Open

TYPE: INTERPRETATION-NHTSA

DATE: FEBRUARY 1, 1990

FROM: SUSAN BIRENBAUM -- ACTING GENERAL COUNSEL, UNITES STATES CONSUMER PRODUCT SAFETY COMMISSION TO: STEPHEN WOOD -- ACTING CHIEF COUNSEL, NHTSA

TITLE: NONE

ATTACHMT: ATTACHED TO LETTER DATED 5-25-90 TO SUSAN BIRENBAUM FROM STEPHEN P. WOOD (A35; VSA 102(4)); ALSO ATTACHED TO LETTER DATED 10-12-89 TO STEPHEN WOOD FROM DAVID SCHMELTZER, U.S. CONSUMER PRODUCT SAFETY COMMISSION, AND LETTER DATED 6-29-89 TO STEPHEN WOOD FROM SUSAN BIRENBAUM. TEXT:

On July 29, 1989, the Consumer Product Safety Commission's Office of General Counsel wrote to your office seeking an opinion as to whether aerosol tire inflator/sealer sold to consumers is an item of "motor vehicle equipment" as that term is defined by t he National Traffic and Motor Vehicle Act. Our Office of General Counsel renewed the request in October. To date we have received no response.

This letter is to advise you that the Commission's Directorate for Compliance and Administrative Litigation is continuing to investigate manufacturers and sellers of this type of product. We have learned of several deaths and serious injuries resulting from the ignition of the gas from these aerosol products contained in tires that were being repaired. The injured and dead include mechanics (or other employees of a repair facility) as well as consumers.

As we investigate this product area, we are encouraging makers and sellers to seek alternate, non-flammable propellants in their tire sealing products. We are attempting to address the potential substantial product hazard we have identified as expeditio usly as possible. This is appropriate in view of our preliminary assessment of the extremely serious risk of injury to consumers using these aerosol products.

This office will seek voluntary corrective action plans from makers and sellers of the various products as the facts show to be appropriate. If voluntary action is not obtained where needed, we will consider the enforcement options available to seek to c ompel corrective measures.

If you need additional information about the product under consideration or any other aspect of this inquiry, please call Allen F. Brauninger of this office at 492-6980.

Thanks again for your assistance with this matter.

ID: nht90-1.35

Open

TYPE: INTERPRETATION-NHTSA

DATE: 02/01/90

FROM: JOHN GARRINGER -- INNOVATION CENTER DRAFTING DEPARTMENT

TO: TERRY M. GERNSTEIN

TITLE: NONE

ATTACHMT: ATTACHED TO LETTER DATED 06/18/90 FROM PAUL JACKSON RICE -- NHTSA TO JOHN W. GARRINGER; A35; STANDARD 205; LETTER DATED 05/07/90 FROM JOHN W. GARRINGER TO STEPHEN P. WOOD -- NHTSA; OCC 4751

TEXT: You have a good idea, but some people would like it plain. If they put it in the glass later on, it would be better plain. If some people would like it with a decoration on it, after we get it on the market we can do it for them. But it is not a novel ty item, it is for safety. So for now, lets get the design patent first.

HOOD GLARE (Design)

The design is; anything that covers the glare that comes from the hood of a car, truck, boat, airplane, or anything that has a hood and windshield, that you can put it on. This will stop the suns glare from coming into the drivers eyes, so he or she can see better. It might become a law, and they will put it inside the glass; (because of being a safety item).

The reason I said plastic is because it's the best and easiest thing to use. But you can use paper, cloth, cardboard, or whatever, just as long as it covers the area, so that the suns glare doesn't hit the drivers eyes.

I have the darkness for the plastic that it will make the suns glare look like a ball, if you have sunglasses on, or a very little glare if you don't have them on. If you put the strip all the way across the windshield you can still see through it.

But if you think that its better to go with your decoration on it, you can go ahead with it, you know what's best since it is your line of work. I do think it would be a good idea to have it decorated and plain and in various colors.

Very Truly Yours,

John Garringer

[DRAWING OF HOOD GLARE OMITTED]

ID: nht90-1.36

Open

TYPE: Interpretation-NHTSA

DATE: February 2, 1990

FROM: Donald C.J. Gray -- Commissioner, General Services Administration, Federal Supply Service

TO: Barry Felrice -- Associate Administrator for Rulemaking, NHTSA

TITLE: None

ATTACHMT: Attached to letter dated 8-31-90 from P.J. Rice to D.C.J. Gray (A36; Part 571.7(c))

TEXT:

The purpose of this letter is to request a deviation from the regulatory provisions of the Federal Motor Vehicle Safety Standards as they apply to school buses procured by the General Services Administration (GSA) for use solely by the Department of the Army. An exception to the standards is provided by 49 CFR 571.7(c) for vehicles or items of equipment manufactured for and sold directly to the Armed Forces of the United States in conformity with contractual specifications. For the reasons stated belo w, we request that this provision be extended to the GSA Interagency Fleet Management System (IFMS) for scbool buses specifically acquired for the sole use of the Army, thereby granting a deviation from the Federal Motor Vehicle Safety Standards otherwis e applicable to such procurements.

In 1985, the Army began a program to consolidate approximately 45,000 nontactical vehicles into the GSA IFMS. The program is fifty percent complete, and, as a result, the IFMS is now responsible for purchasing and leasing vehicles for the sole use of th e Department of the Army.

Prior to consolidation, the above cited provision permitted the Army to acquire vehicles manufactured to satisfy multiuse requirements. The Army acquired school buses equipped with seating designed for adults, and painted in a color other than school bu s yellow. The Army buses were utilized for their primary mission of troop movement, and, as needed, for transporting military dependents to and from school. Because 49 CFR 571.7(c) makes the standards inapplicable to vehicles manufactured for and sold directly to the Armed Forces, the Army avoided the cost of a second bus specifically designed for use by school children.

For the Government to continue to realize this cost avoidance, a deviation must be granted from the Federal Motor Vehicle Safety Standards for vehicles or items procured by the GSA IFMS for use solely by the Army. This deviation would thereby extend the exception of 49 CFR 571.7(c) to permit the Department of the Army to use GSA IFMS supplied buses for both adults and school children.

If we may provide any assistance or further information concerning this request, please contact Mr. Sean Allan of the Fleet Management Division on 557-1278.

ID: nht90-1.37

Open

TYPE: Interpretation-NHTSA

DATE: February 2, 1990

FROM: Philip A. Hutchinson, Jr. -- Vice President, Public Affairs, General Counsel & Secretary, Volkswagen of America, Inc.

TO: Jerry Ralph Curry -- Administrator, NHTSA

TITLE: Re CAFE Exemption Pursuant to 15 USC 2003(b)(3)

ATTACHMT: Attached to letter dated 10-1-90 from P.J. Rice to P.A. Hutchinson, Jr. (A36; CSA Sec. 503(b)(3))

TEXT:

This is to notify you that Volkswagen of America, Inc. (VWoA) is no longer manufacturing automobiles in the United States and that its exemption from 15 USC 2003(b)(1) granted on October 23, 1981 and published in 46 F.R. 54453 of November 2, 1981 has bec ome moot and is therefore effectively terminated.

On July 29, 1981 VWoA filed a petition pursuant to 15 USC 2003(b)(3)(A) seeking an exemption from the general statutory requirement that fuel economy ratings for imported passenger automobiles may not be averaged together with ratings from domestically m anufactured passenger automobiles for the purpose of determining compliance with the Motor Vehicle Information and Cost Savings Act, as amended. 15 USC 2003(b)(3)(B) authorizes exemptions to be granted for a period of five years or, at the request of th e manufacturer, such longer period as the agency may specify. VWoA requested that the exemption be granted indefinitely and the agency acceded to this request subject to its right to reconsider its action "should it appear that the exemption is no longer consistent with the purposes of the Act." (46 F.R. 54453)

VWoA sought an exemption of indefinite duration because it expected to maintain a domestic assembly facility indefinitely. The exemption was intended by VWoA to remove a possible disincentive associated with the expected increase in the domestic content in US produced passenger automobiles above 75% in the event VWoA imported and domestic passenger vehicle fleets were not capable separately to comply with CAFE standards.

The exemption was granted on October 23, 1981 and made effective beginning with the 1982 model year.

For model year 1982 VWoA distributed "imported" passenger vehicles only.

For model years 1983 through 1987 VWoA distributed both "imported" and "domestic" passenger automobiles as defined in 15 USC 2003(b)(1) and (b)(2)(E) and (F). The manufacture of "domestic" passenger automobiles within the meaning of the Act ended on Jun e 30, 1987. Effective July 14, 1988 VWoA shut down its entire production in the United States so that commencing with the 1988 model year only "imported" vehicles have been offered for sale in the United States by VWoA.

15 USC 2003(b)(3)(F) provides that "Notwithstanding section 2002(1) of this title, in the case of any model year for which an exemption under this subsection is effective for any manufacturer", the manufacturer may not earn or use any credit pursuant to 15 USC 2002(l)(1)(B) and 2002(l)(1)(C).

Since VWoA discontinued all vehicle assembly in the United States effective July 14, 1988, the exemption granted on October 23, 1981 should be deemed to have been mooted at least since July 1988. It should be noted, moreover, that the exemption has prod uced no "effect" on VWoA's status of compliance of its passenger vehicle fleet with CAFE requirements, i.e. has not been "effective for VWoA" within the meaning of Section 2003(b)(3)(F) and conferred no benefit on VWoA since June 30, 1987 when the last p assenger automobile with domestic content in excess of 75% was manufactured in the United States.

Based upon the facts set forth above, VWoA maintains that the prohibition against accumulation of fuel economy credits ended on June 30, 1987 but in no event later than July 14, 1988.

Please advise us of NHTSA's position on this matter. In the interest of certainty VWoA is interested in knowing the amount of credits which have accumulated in its account.

Thank you for your assistance.

ID: nht92-8.16

Open

DATE: March 26, 1992

FROM: Paul Jackson Rice -- Chief Counsel, NHTSA

TO: Larry J. French -- President and CEO, Magnascreen

TITLE: None

ATTACHMT: Attached to letter dated 1/24/92 from Larry J. French to Office of the Chief Counsel, NHTSA (OCC 6921)

TEXT:

This responds to your letter inquiring about a recent amendment to Safety Standard No. 111, Rearview Mirrors. (49 CFR S571.111) You explained that your company is developing electronically controlled dimmable (day/night) rearview mirrors for motor vehicles and requested that the agency assess your reading of section S11 of the standard. We are pleased to have this opportunity to interpret our standard for you.

By way of background information, the National Highway Traffic Safety Administration (NHTSA) does not provide approval of motor vehicles or motor vehicle equipment. Under the National Traffic and Motor Vehicle Safety Act, the manufacturer is responsible for certifying that its vehicles or equipment comply with applicable standards. The following letter represents our opinion based on the facts presented in your letter.

Safety Standard No. 111 specifies requirements for the performance and location of rearview mirrors. Section S11, which was recently amended to better address new mirror designs, specifies requirements for mirror construction. (See 56 FR 58513, November 20, 1991.) The section states in relevant part that:

All single reflectance mirrors shall have an average reflectance of at least 35 percent. If a mirror is capable of multiple reflectance levels, the minimum reflectance level in the day mode shall be at least 35 percent and the minimum reflectance level in the night mode shall be at least 4 percent. A multiple reflectance mirror shall either be equipped with a means for the driver to adjust the mirror to a reflectance level of at least 35 percent in the event of electrical failure or achieve such reflectance level automatically in the event of electrical failure.

You asked whether an alternate power source can be used to achieve the specified fail-safe operation (i.e., adjusting the mirror to a reflectance level of at least 35 percent in the event of electrical failure). While your letter did not specify what you meant by "alternate power source," we assume that it means an electrical power source other than the one intended to normally operate the mirror. Examples of an alternate electrical power source include solar energy or a self-contained battery system.

We interpret the term "electrical failure," as used in section S11 of Standard No. 111, to include any type of electrical failure. This would include electrical failure related to an alternate power source as well as electrical failure related to the primary power source. Therefore, unless adjustment of

the mirror to a reflectance level of at least 35 percent occurred even in situations where there was electrical failure related to the alternate power source, the alternate electrical source could not be used to provide the fail-safe operation required by section S11.

The preamble to the final rule amending Standard No. 111 explained that the agency wanted to assure that multiple reflectance mirrors are capable of providing adequate images at all times during this vehicle's operation, including electrical failure situations where the mirror is unpowered. The agency noted that situations can occur where the mirror would be unpowered even though the vehicle could be operational, citing connector faults and circuit board faults. See 56 FR 58515.

To comply with section S11 in situations where a mirror is unpowered as a result of electrical failure, a mirror would either have to default automatically to the high reflectance mode (as in the case of an opposite polarity fail-safe liquid crystal mirror described in the preamble) or be capable of being manually adjusted to the high reflectance mode. We do not have enough information about your proposed mirror to determine whether it would comply with the amendments in the case of electrical failure related to the alternate power source.

I hope this information is helpful. If you have any further questions about NHTSA's safety standards, please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992.

ID: nht92-8.17

Open

DATE: March 26, 1992

FROM: Michael J. Sens -- Researcher, S.E.A., Inc.

TO: Paul Jackson Rice -- Chief Counsel, NHTSA

TITLE: None

ATTACHMT: Attached to letter dated 4/17/92 from Paul J. Rice to Michael J. Sens (A39; Std. 206; Part 571; Part 567)

TEXT:

By way of this letter, I am seeking an interpretation of FMVSS 206, 214, and 216 as they would pertain to a 1985 Jeep CJ-7. The Jeep CJ-7 was classified (it is no longer in production) by its manufacturer, American Motors Corporation, as a "sport-utility vehicle". The vehicle came with a soft top and a removable fiberglass top option. The side doors are easily removable.

FMVSS 206, "Door Locks and Door Rentention Components," requires at S4. that "components on any side door leading directly into a compartment that contains one or more seating accommodations shall conform to this standard." It goes on to say, "However, components on folding doors, roll-up doors and doors that are designed to be easily attached to or removed from motor vehicles manufactured for operation without doors need not conform to this standard". My first question is: since the 1985 Jeep CJ-7's side doors are easily attached and removed by design for operation in a doorless manner, is it exempt from conformity to FMVSS 206?

FMVSS 214, "Side Door Strength," states at S2. that "this standard applies to passenger cars." The 1985 Jeep CJ-7 is defined by its manufacturer as a "sport-utility vehicle." This classification is not that of a "passenger car." My second question is: since the 1985 Jeep CJ-7 is classified as a "sport-utility vehicle," does FMVSS 214 apply to it?

FMVSS 216, "Roof Crush Resistance-Passenger Cars," states at S3. that "This standard applies to passenger cars." After stating that it does not apply to vehicles that conform to the rollover test requirements of S5.3 of standard 208, it continues, "It also does not apply to convertibles." My third question is: since the 1985 Jeep CJ-7 is classified as a "sports-utility vehicle" and is a convertible, does FMVSS 216 apply to it?

Please find enclosed two views of the type vehicle under discussion. The 1985 CJ-7 shows the soft-top package with the top down and the side doors removed. Unfortunately, I do not have an illustration of the 1985 CJ-7 with the optional hard snap-on top. However, the 1981 CJ-7 model photograph enclosed is typical of how the 1980's CJ-7 line appeared with the optional top.

Thank you in advance for your time and considerations on this issue. If you require additional information, do not hesitate to contact me.

Attachment

Photos and text pertaining to the 1981 and 1985 CJ-7 vehicles.

(Text and graphics omitted)

ID: nht92-8.18

Open

DATE: March 26, 1992

FROM: Paul Jackson Rice -- Chief Counsel, NHTSA

TO: Charles W. O'Conner -- Assistant Secretary, Echlin Inc.

COPYEE: Larry Henneberger; Bill Lewandoski; California Highway Patrol

TITLE: None

ATTACHMT: Attached to letter dated 12/26/91 from Charles W. O'Connor to Paul J. Rice (OCC 6863)

TEXT:

This responds to your letters of December 26, 1991, and February 25, 1992, with respect to various interpretive letters of this Office on the Commander and Voyager Electronic Brake Control ("Control"). The Control is manufactured by your subsidiary, Tekonsha Engineering Company. For the reasons enunciated in your December letter, you have asked us to "rule that all three of your letters i.e., the November 22 and May 23, 1991, letters to Mr. Lewandoski and your letter of September 10, 1990, to Mr. Henneberger are all void from the beginning."

We are replying on the basis of information presented by representatives of Tekonsha, Mr. Henneberger, and yourself in a meeting with representatives of NHTSA on March 18, 1992, rather than on the basis of your December letter. This meeting brought forth facts, previously unknown to us, and which did not, therefore, form a basis for the three previous letters on this subject mentioned above.

We now understand that the Control is motor vehicle equipment which is added to the towing vehicle by the seller of the towed vehicle, at a time subsequent to the first purchase of the towed vehicle for purposes other than resale. The Control has no effect upon the stop lamp system of the towing vehicle. The Control in ordinary operation has no effect upon the stop lamp system of the towed vehicle. When hand-activated in an emergency mode, the Control applies a modulated pressure to the service brakes of the towed vehicle, without activating the stop lamps on the towed vehicle. It is theoretically possible that the Control will never be operated during the life of the towing vehicle.

It is our opinion that the applicable Federal law in this situation is that which pertains to the operation of vehicles in use, rather than the Federal motor vehicle safety standards that apply to motor vehicles before their first purchase for purposes other than resale. This means that we do not view this as a question of compliance with Federal Motor Vehicle Safety Standard No. 108 or a matter concerning the preemption of State statutes by Standard No. 108.

Under the statutes and regulations we administer, the applicable law is 15 U.S.C. Section 1397(a)(2)(A). This Section states in pertinent part:

"No manufacturer, distributor, dealer, or motor vehicle repair business shall knowingly render inoperative, in whole or in part, any device or element of design installed on or in a motor vehicle or motor vehicle equipment in compliance with an applicable Federal motor vehicle safety standard . . . ."

The question therefore is whether the installation of the Control on the towing vehicle by the dealer of the towed vehicle renders the stop lamps (installed on the towed vehicle in compliance with Standard No. 108) inoperative in whole or in part within the meaning of Section 1397(a)(2)(A).

We note that the installation per se of the Control has no effect of any sort on the stop lamps of the vehicle on which it is installed, or on the vehicle that is towed. Therefore, the dealer has not rendered any stop lamps inoperative by the act of installing the Control. It is the use of the Control that may have an effect upon the stop lamps. In ordinary use, the Control has no effect upon the stop lamps of either the towing or towed vehicle. However, when the hand control of the device is activated in the emergency mode on the towing vehicle, to slow the swaying of the towed vehicle through application of the only set of brakes on the towed vehicle (its service brakes), the stop lamps will not be activated. In the conscious act of activating the emergency feature, the operator has knowingly rendered the stop lamps on the towed vehicle inoperative for the duration of such activation (unless or until the operator applies the service brake of the towing vehicle). However, Section 1397(a)(2)(A) does not apply to operators, thus the activation and use of the Control is not prohibited under our Statutes and regulations.

On the basis of the facts presented in the meeting on March 18, it now appears that the sale of the control is not in violation of the National Traffic and Motor Vehicle Safety Act.

ID: nht92-8.19

Open

DATE: March 24, 1992

FROM: George F. Reuss -- Reuss Engineers, Inc.

TO: Barry Felrice -- Associate Administrator for Rule Making, NHTSA

TITLE: None

ATTACHMT: Attached to letter dated 4/29/92 from Paul J. Rice to George F. Reuss (A39; VSA 102 (3))

TEXT:

Reuss Engineers Has received a patent for a propietary vehicle to pick up and transport autombiles. We have produced a practical prototype and are ready to produce commercial models for sale. We are interested in knowing which specific regulations and standards apply.

The complete vehicle consists of a purchased chassis with a GVWR greater than 10,000 pounds. Between the cab and the rear wheels is inserted a structural frame including moveable forks that can be extended from the framework and inserted beneath an automobiles' tires. The forks are raised, carrying the automobile with them, and retracted into the frame work. The vehicle containing the automobile is driven to any destination and the proceedure reversed.

Enclosed are 2 pages of the patent giving a pictorial representation.

We appreciate any help and guidance. Thank yo for your prompt attention.

Attachment

Copy of patent number 5,067,869, dated 11/26/91. (Text and graphics omitted.)

ID: nht92-8.2

Open

DATE: April 3, 1992

FROM: Paul Jackson Rice -- Chief Counsel, NHTSA

TO: Charles Danis -- Les Enterprises Track Test Inc. (Quebec)

TITLE: None

ATTACHMT: Attached to letter dated 2/7/92 from Charles Danis to Paul J. Rice (OCC 6991)

TEXT:

This responds to your letter about testing related to Federal motor vehicle safety standard No. 121, Air Brake Systems, (49 CFR S571.121). You explained that your company has recently conducted a compliance test on an articulated bus manufactured by MCI Greyhound Canada. According to your letter, the buses were tested using 28 psi for the brake actuation test and 40 psi for the brake release test. While these air pressures differ from the pressures specified in S5.3.3 and S5.3.4 for brake actuation and release times, you stated that MCI was relying on a July 23, 1976 interpretation issued by the agency to Mr. J.W. Lawrence of the White Motor Corporation that permitted such brake actuation and release pressures. We note that to be consistent with that interpretation, the maximum brake chamber pressure must have been 40 psi when the service reservoir pressure was at 100 psi. Your letter was not clear on that point. You asked whether this interpretation is still valid. As explained below, the answer is yes.

In its inquiry to NHTSA, White Motor Corporation asked whether S5.3.3 and S5.3.4 of Standard No. 121 require minimum brake chamber actuation and release time pressures of 60 psi and 95 psi, respectively, or whether these air pressures are included in the sections only as "bench marks" on which to base specifications for minimum actuation and release timing. In response, the agency's July 23, 1976 interpretation letter stated in relevant part that:

Your understanding that S5.3.3 and S5.3.4 only specify the air pressures of 60 psi and 95 psi as the basis for timing requirements is correct. Neither value is intended as a requirement that the vehicle be designed to provide a certain level of brake chamber air pressure.

The values were based on an understanding of the typical configuration of existing air brake systems at the time the final rule was issued.

In response to your specific question, NHTSA's July 23, 1976 interpretation letter continues to be valid.

I hope this information is helpful. If you have any further questions about NHTSA's safety standards, please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992.

Request an Interpretation

You may email your request to Interpretations.NHTSA@dot.gov or send your request in hard copy to:

The Chief Counsel
National Highway Traffic Safety Administration, W41-326
U.S. Department of Transportation
1200 New Jersey Avenue SE
Washington, DC 20590

If you want to talk to someone at NHTSA about what a request for interpretation should include, call the Office of the Chief Counsel at 202-366-2992.

Please note that NHTSA’s response will be made available in this online database, and that the incoming interpretation request may also be made publicly available.

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